For successful oil and gas exploration, information about the subsurface formations that are penetrated by a wellbore is necessary. Measurements are essential to predicting the production capacity and production lifetime of a subsurface formation. Collection and sampling of underground fluids contained in subterranean formations is well known. In the petroleum exploration and recovery industries, for example, samples of formation fluids are collected and analyzed for various purposes, such as to determine the existence, composition and producibility of subterranean hydrocarbon fluid reservoirs. This aspect of the exploration and recovery process is crucial to develop exploitation strategies and impacts significant financial expenditures and savings.
Samples of formation fluid, also known as reservoir fluid, are typically collected as early as possible in the life of a reservoir for analysis at the surface and more particularly, in specialized laboratories. The information that such analysis provides is vital in the planning and development of hydrocarbon reservoirs, as well as in the assessment of the capacity and performance of a reservoir.
One technique for sampling formation fluid from subterranean formations and conducting formation tests often includes one or more inflatable packer assemblies or packers (e.g., straddle packers) to hydraulically isolate or seal a section of a wellbore or borehole that penetrates a formation to be tested or sampled. Such inflatable packer assemblies typically include a flexible packer element made from an elastomeric material that is reinforced with metal slats or cables. However, due to the harsh conditions (e.g., high temperatures) within many boreholes, the elasticity and mechanical strength of the elastomeric material of the packer element may become significantly compromised. Thus, a packer may be inflated to seal against a portion of the borehole and may retain a relatively large outside diameter after the inflation pressure has been released. In some cases, the outside diameter of the previously inflated packer may be large enough to prevent the downhole tool to which it is attached from being removed from the borehole, thereby resulting in a costly well repair and/or tool recovery operation.
Additionally, in applications where an inflatable packer is used with a downhole tool deployed via a drill string, a packer element may inadvertently expand as a result of the rotation and become wedged in the borehole. This may cause the packer to become damaged or may even result in the tool becoming stuck in the borehole.